The present invention relates to a method for displaying a map, and more particularly to a method for displaying a predetermined area on a map in a navigation system for a motor vehicle.
Recently there has been developed a vehicular navigation system which can display map information prestored in a memory together with an indication on the map of the vehicle's present position, to thereby allow the driver to easily determine the best route to the desired destination.
In such a navigation system, when the map is displayed on a display unit, areas such as rivers, streams, lakes, wooded tracts, and the like are indicated by specific corresponding colors so that these areas are easy to pick out. This "painting" operation is performed with respect to the boundaries of the specific area to be displayed in color on the display unit. That is, a start point for painting is chosen within the boundaries of the specific area, and the area is then filled in with the designated color up to the boundaries. Only one start point is ordinarily required for each area to be painted.
The above system includes a memory for storing digital data indicating the start and end points of line segments defining the boundaries of the areas to be painted, together with data indicating the start point for the painting operations. Thus actual painting operation of the predetermined area begins at thus-designated start point.
The range which can be displayed on the display unit is limited by the surface size of the display unit and, therefore, the entirety of the area to be painted may not be displayed on the display unit but may be divided between displayed and nondisplayed portions The conventional system is disadvantageous in that there is a possibility that the predetermined area displayed on the display unit thus may not contain the designated start point for the painting operation. If such occurs, the user must manually input a new start point for the painting operation, making the input operation for the system complex.